Prior art round balers generally have a bale forming chamber defined by an array of side-by-side belts, transverse slats trained on chains, a plurality of rolls or a combination of these various elements. Crop material is picked up from the ground and fed into a chamber where it is spirally rolled to form a compact cylindrical hay package. While inside the chamber in its compacted form, the outer surface of the package is wrapped with twine or web material, such as net, to form a bale which is then ejected from the chamber for subsequent handling.
Exemplary of prior art round balers of the general type mentioned above is the baler disclosed in U.S. Pat. No. 4,956,968 issued in the name of K. R. Underhill on Sep. 18, 1990. In this baler a combination of rolls and belts is used for bale formation. The baler also includes a mechanism for supplying net to a dispensing assembly which in turn feeds the net into the bale forming chamber for wrapping a cylindrical package of crop material. The dispensing mechanism includes a net insertion arrangement having a grasping portion for taking net from the supply mechanism and inserting the free edge, commonly referred to as the tail, into the chamber. Subsequent to wrapping, the net material is severed by a cutting device, comprising an assembly that drops a knife in a free falling fashion into the path of the taut net causing a severing action as the bale rotates and pulls the net against the knife edge. After the net is severed, the bale is ejected rearwardly by lifting the tail gate to open the chamber.
In the arrangement noted above, it is important that the free falling knife step be properly coordinated with other functional steps of the baler. This coordination is especially critical because cutting takes place in an area where the dispensing mechanism projects during the time that net is being dispensed into the chamber. Serious damage would result if the cutting and wrapping functions were initiated at the same time due to a simple malfunction of their respective control mechanisms, operator error, etc. In U.S. patent application Ser. No. 07/931,801, filed Aug. 18, 1992 in the name of Kenneth R. Underhill, et al, and assigned to a common assignee, a round baler mechanism is disclosed which deals with this problem. The mechanism controls a latch that will not release a free falling knife assembly until after the wrapping mechanism has been properly sequenced.
Another example of the importance of coordinating various round baler functions is highlighted by the situation where a free falling knife assembly is dropped before the net is properly presented, regardless of whether other mechanisms are in the path of the knife. Among the problems arising in this situation would be a ragged or uneven cut, premature cutting, i.e., before the proper number of wraps are applied, a missed cut due to slack net which leads to the need for manual intervention and a myriad of other problems brought on by the complexities of the sequential steps in the automated balers for which the mechanism is designed.